In general, a data logging apparatus of a condition monitoring system is used to measure or control the temperature, vibration, flow rate, pressure or the like.
Parts sensitive to surrounding physical environments, e.g. a loading container used for carrying semiconductor wafers, can be susceptible to unfavorable environmental conditions. For example, due to the unfavorable environmental conditions within the loading container (e.g., temperature, humidity and/or pressure), gas can be produced from the loading container (typically, the loading container is formed of a resin material), and contents stored within the loading container (e.g., semiconductor wafers) can be contaminated due to the produced gas. Further, shock and vibration applied to the loading container may create relative motions between the container and the contents therein. The relative motions or friction between the loading container and the contents such as semiconductor wafers can lead to the generation of particulates (the particulates are produced from the wafer materials as well as the loading container), and accordingly, such particulates can contaminate the wafers stored in the loading container.
If the semiconductor wafers are affected by any one of the aforementioned environmental conditions while they are carried, the resultant damages (e.g., fine fractures, chemical contamination, or particulate contamination) are often indistinguishable and difficult to find out. In addition, such damages (or influences from such damages) are hardly noticed until the manufacture of integrated circuit (IC) devices is almost completed (i.e., until a final electrical test). As a result, not only the loss of the damaged IC parts but also the loss of resources consumed to dispose of damaged devices that cannot be manufactured into marketable products are incurred. Accordingly, significant environmental damages can lead to low production yield and high production costs.
A data logging apparatus is attached directly to a loading container for carrying an object sensitive to surrounding physical environments, such as semiconductor wafers, or to a packing box of the object to measure and store the changes in physical quantities occurring while the object is carried, so that the measure and stored quantities are used as base data required for analyzing the shipping environments.
However, since the conventional data logging apparatus is attached directly to an object or is carried together with the object, electric power is supplied by a battery. Thus, there is a problem in that data on the physical quantities are not logged if the battery is discharged due to the use of the data logging apparatus for an extended period of time.
Further, only predetermined physical quantities can be measured in accordance with the types of installed sensors, and thus, there is disadvantage in that the data logging apparatus is not sufficiently compatible when measuring physical quantities according to characteristics of various kinds of objects. Particularly, if an installed sensor is out of order, the whole apparatus should be disassembled or replaced to exchange the sensor with another new one.
In addition, if the aforementioned measuring apparatus is installed to monitor the state of fixtures, such as fences, installed in an extended area, measured data from the measuring apparatus are transmitted to a main center via wireless or wired communication. Since the remotely installed measuring apparatus that is remote from the main center should transmit signals of high output power to communicate with the main center in a wired or wireless way, power consumption is too high. Accordingly, there is a problem in that data are not logged due to the discharge of battery.